Purpose :
We recently reported that retinal stimulation with flickering light increases retinal blood flow (RBF) in anesthetized cats, indicating tight coupling between the neural activity and blood flow, namely “neurovascular coupling.” Although many clinical studies have reported that vasodilation of the retinal vessels elicited by flicker stimuli was impaired in patients with diabetes, no study has evaluated the RBF in those patients. The aim of the present study was to investigate whether the RBF response is altered in patients with type 2 diabetes mellitus with no retinopathy.

Methods :
Seventeen patients with diabetes mellitus with no retinopathy and eight age-matched healthy volunteers were included. We measured the retinal arteriolar diameter (D) and velocity (V) and calculated the RBF with laser Doppler velocimetry. The second-order retinal arterioles were studied. The eyes were dark-adapted for 15 minutes before presentation of flicker stimulation with a frequency of 16 Hz for 180 seconds.

Conclusions :
Our clinical data showed that the flicker-induced RBF response may be impaired in patients with type 2 diabetes with no retinopathy. Whether this diminished response can be attributed to altered retinal vascular reactivity or to decreased neural activity has yet to be clarified.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.